What is forced vital capacity (FVC)?

Forced vital capacity (FVC) is the amount of air that can be forcibly exhaled from the lungs after taking the deepest possible breath.it is from Spirometerwhich is a common breathing test to check lung function.

This test may help differentiate between obstructive and restrictive lung disease. Obstructive diseases, such as asthma and chronic obstructive pulmonary disease (COPD), make it difficult to get all the air out of your lungs.restrictive lung diseases such as pulmonary fibrosis and sarcoidosiscausing inhaled air to fill the lungs.

FVC can also help healthcare providers assess the progression of lung disease and assess the effectiveness of treatment. Abnormal FVC values ​​can be chronic, but sometimes the problem is reversible and FVC can be corrected.

This article discusses the purpose of the FVC test. It covers what to expect during testing and how the results should be interpreted.

Purpose of FVC

FVC is used to assess your lung function. It measures how your lung disease affects your ability to inhale and exhale.

While FVC cannot determine which specific lung disease you have, the results can help narrow down the potential diagnosis. It can be used along with other research to help determine which lung disease you have.

Reasons you might need to measure FVC include:

  • You have shortness of breath, a persistent cough, or wheezing.
  • Your healthcare provider will want to assess your respiratory function when your blood oxygen levels are low.
  • You are having surgery. It is important to know if your breathing is stable before surgery, especially if you will have lung surgery.
  • You have heart disease and its impact on your ability to breathe needs to be assessed.
  • You and your healthcare provider are planning your pulmonary rehabilitation program.
  • You have reached the endpoint of a clinical trial expected to affect lung function.

Related tests

When you go to measure your FVC, you may have other tests. These include your vital capacity (VC) and forced expiratory volume in one second (FEV1).

FVC and VC record similar information. They both measure the amount of air you can exhale after inhaling at the maximum. But FVC is the amount of air you can forcefully exhale. VC records the maximum amount of air exhaled during normal breathing.

The FEV1 is different in that it measures the amount of air you can exhale in one second.

Your FVC and other pulmonary function tests (PFTs) are used to determine your lung function status. They compare your measurements to standards based on your age, gender, ethnicity, height and weight.


The FVC test measures the amount of air you can forcefully exhale after taking a deep breath. When used with other lung tests, it can help your doctor diagnose which lung disease you have.

Risks and Contraindications

FVC requires your cooperation and effort, but it is safe. However, it is important that you are under medical supervision the first time you use a spirometer (a device used to measure FVC). You could be using your spirometer the wrong way and exhausting yourself.

After that, you may be instructed on how to use it yourself at home. You should ensure that the spirometer you use is thoroughly cleaned before each use. That way you don’t come into contact with anything that could lead to an infection.

If a friend or family member uses a home spirometer, do not use their device to measure your FVC or perform other lung function tests.

before testing

Before your FVC test, your healthcare provider may give you instructions about medication. You may also be instructed to use your inhaler (or other treatment) so that your medical team can assess how well it is working.

A lung infection or exposure to cigarette smoke can also affect your results. It’s important to discuss these issues with your healthcare provider before getting tested. Your FVC may be rescheduled if needed.


The FVC test itself should only take a few minutes. Be sure to ask your healthcare team how long you should be at the testing site.

There are other aspects of lung testing, such as functional residual capacity (FRC), which measures the air in the lungs after exhalation. If your lung disease is difficult to diagnose, or if your condition is not improving as expected, you may need additional tests.

Your full test may take an hour or more.


You will have an FVC test done in your healthcare provider’s office or lung testing laboratory.

what to wear

Be sure to wear loose-fitting clothing so you don’t feel restricted when breathing. It is important that you can inhale and exhale as deeply as possible during the test.


You don’t need to make any adjustments to your food and drink before or after taking the FVC test.

Fees and Health Insurance

The price of the test is between $40 and $80. If you have health insurance, your carrier may cover all or part of the cost. Be sure to check with your insurance company to ask if you need to pay a copay or the full cost of the test.

Keep in mind that your total cost will be higher if you have other lung tests.

what to bring

Bring a list of all your medications, a piece of identification, your health insurance information, and a payment method.

Also, keep your inhalers with you, even if you have been instructed not to use them before the test.You may be asked to use an inhaler period your test.


Your healthcare provider will tell you whether you should use an inhaler or other medication before the test. The FVC test may only take a few minutes. It’s usually done in your healthcare provider’s office or lung testing lab.

During the test

When you arrive to take the test, you will be asked to log in and provide your paperwork. You will meet a medical team, which may include technicians, nurses and/or doctors.

throughout the test

Spirometry is non-invasive and only takes a few minutes. Other lung function tests may be performed at the same appointment.

FVC spirometry is performed as follows:

  1. You sit in a chair and are asked to breathe comfortably.
  2. A clip is placed on your nose.
  3. You will get a tube for you to breathe.
  4. Sealing your lips tightly against the tube asks you to inhale as deeply as possible. Then you exhale as hard as you can.

This process was repeated at least 3 times to obtain consistent averages.

after test

After completing the FVC test, you will most likely not need any recovery time. After the test, you will usually need the same care and support that you would normally need. If you have severe lung disease, this support may include supplemental oxygen or paramedics to help you get around.

Be sure to tell your healthcare team if you feel dizzy or short of breath. You may be asked to sit for a few minutes while you recover.

Also, if you have persistent or severe symptoms, you may need to have your oxygen levels checked. If it’s low, you’ll get supplemental oxygen.


During the test, you will be given a tube for you to inhale, inhale deeply, and exhale forcefully. You may need to repeat 3 times to get an average measurement. If you feel dizzy or short of breath, you may be asked to sit for a few minutes to recover.

Interpret the results

Your total FVC can be compared to standard FVC for your age, gender, height and weight. Your FVC can also be compared to your own previous FVC value. This can determine if the condition of your lungs is getting worse, or if your lung function is improving.

Mandatory vital capacity will be reported in two ways:

  • As an absolute value, reported in liters (L)
  • Plotting expiratory dynamics on a linear graph

The normal FVC range for adults is between 3.0 and 5.0 L.

For children, a reference table that includes the child’s height, weight, and other factors can be used to predict the expected FVC. For example, the standard FVC for an average-sized preschool boy is 1.16 L, while the standard FVC for an average-sized preschool girl is 1.04 L.

FVC can also be expressed as a percentage of predicted FVC.

FVC reduction

Forced vital capacity can be temporarily or permanently reduced. Decreased FVC values ​​are a sign of several conditions, including:

  • Chronic obstructive pulmonary disease (COPD), including chronic bronchitis, emphysema, and Bronchiectasis
  • Restrictive airway disease, such as idiopathic pulmonary fibrosis
  • Structural restrictive airway disease, such as those caused by scoliosis and scarring of the chest
  • Diseases such as sarcoidosis
  • Inflammatory lung diseases such as asbestosis and silicosis
  • lung cancer

FEV1/FVC ratio

Your FVC value can be used to calculate your FEV1/FVC ratio. The ratio of FEV1 to FVC compares the amount of air that can be forcibly expelled in one second to the total amount of air that can be expelled. The normal FEV1/FVC ratio is 70% to 80% or higher in adults and 85% or higher in children.

The FEV1/FVC ratio can help determine whether lung disease is obstructive (eg, COPD) or restrictive (eg, pulmonary fibrosis). Any change in the FEV1/FVC ratio can provide valuable information on whether pulmonary obstruction and/or pulmonary restriction has occurred.

While restrictive illnesses limit air intake, they don’t by themselves affect your ability to exhale. By contrast, obstructive disorders can make it difficult to exhale, but they do not necessarily change the capacity of the airways.

have a restrictive disease

  • Both FEV1 and FVC are scaled down to equalize the FEV1/FVC ratio.

have obstructive disease

  • The FEV1/FVC ratio will be below 70%.

If both the FEV1/FVC ratio and FVC are low, the individual has a mixed defect of restriction and blockage.

follow up

After completing the FVC or calculating the FVC/FEV1 ratio, you may need to perform further testing.

For example, respiratory symptoms with a normal FEV1/FVC ratio suggest a restrictive pattern. You may need comprehensive lung function tests and imaging studies such as computed tomography (CT) of the chest/lungs.

Obstructive pulmonary disease is indicated if the FEV1/FVC ratio is low. Your healthcare provider may repeat the test with a bronchodilator to see if the blockage is reversible. Obstructive diseases such as asthma are often reversible, whereas diseases such as chronic obstructive pulmonary disease are not.

Once you’ve been diagnosed with a lung disease that affects your FVC, you may need to repeat this test regularly. This way your medical team can continue to monitor your condition.


Follow-up tests may include lung function tests, chest/lung CT scans, or bronchodilator tests. These can help narrow down which type of obstructive or restrictive lung disease you have.


The FVC test helps assess your lung function. It measures how much air you can forcefully exhale after taking a deep breath. This can help determine if you have an obstructive lung disease that makes it difficult to breathe out, or a restrictive condition that makes it difficult to breathe in.

When you are tested, your doctor will ask you to breathe through a tube. You take a deep breath and blow as hard as you can. You may be asked to bring an inhaler to your appointment to see how it affects your lung function.

After that, your healthcare provider may order follow-up tests, such as imaging tests, to help diagnose your condition.

VigorTip words

While FVC is an important measure of lung disease, it is important to remember that it is only a number. Your healthcare provider will review your medical condition, general health and other findings. This will help them understand how your FVC measurement fits into the bigger picture of your health.